This invention relates to a power control device and more particularly but not exclusively to a power control device for controlling power available to a motor, in order to control motor speed. The invention has been developed primarily for use in controlling the speed of a windscreen wiper motor for an aircraft, but may be used for controlling motor speeds in other applications, or indeed for controlling the power available for a light in order to vary the intensity of the light, or otherwise where it is desired to control power available to an electrical load.